The invention relates to an entry conveyor, particularly an entry transfer conveyor or crusher conveyor, comprising a conveyor pan formed by a plurality of pan sections that are hingeably connected to each other in a manner that guarantees tensile strength, at the two ends of which conveyor pan drive stations and/or return stations for a double scraper chain are provided, wherein each pan section comprises a top strand delimited by lateral profiles and the conveyor base and a bottom strand for the scraper chain as well as receiving elements for pan section connecting means, which elements are disposed outside of the lateral profiles. The invention furthermore relates to a pan section for corresponding entry conveyors, comprising a top strand, which is delimited by lateral profiles and a conveyor base, a bottom strand formed beneath the top strand and receiving elements for pan section connecting means on the outsides of the lateral profiles.
In the underground mining of minerals, particularly underground coal mining, downstream of the face conveyor provided in the mining longwall face an entry transfer conveyor is provided, in which generally a crusher is integrated, which reduces the previously mined mineral material to a size that can subsequently be transported by means of conveying belts. Both the face conveyor and the entry transfer conveyor are configured as scraper chain conveyors, which comprise robust double scraper chains with scraper blades connected to the chain links at regular intervals, which blades are used to transport the material. As a result of the mining progress that is made, the current position of the transfer station will change from a face conveyor to an entry conveyor. Since the crusher overall forms the heaviest unit, it is generally not moved or only in a linear fashion, and the crusher is frequently disposed in the vicinity of the return unit that is raised by means of a loading ramp, which unit at the same time forms a discharge station onto a downstream conveying belt or the like. Based on these circumstances, frequently position changes arise between the crusher on the one hand and the face entry transfer station on the other hand, which changes result in relatively high bending of the hingeably coupled pan sections of the entry conveyor. The hinged movement of the pan sections is guaranteed by means of pan section connecting elements, which are disposed on both sides of the lateral profiles and/or the conveyor pan and which connect adjoining pan sections of an entry conveyor in a manner that guarantees tensile strength, however at the same time allow the necessary hinged movement. Despite the short length in comparison with face conveyors, face-entry conveyors are subject to high chain forces and high chain tension, which can lead to disproportionate wear of the pan sections of the entry conveyor and/or the scraper chains that are used.
It is the object of the invention to create an entry conveyor and/or pan sections for an entry conveyor with improved operating behavior and reduced proneness to wear.
This object is achieved according to the invention in that on the entry conveyor in the conveyor pan a pan strand comprising a plurality of pan sections disposed behind each other is formed, which sections are hingeably coupled by means of a center swivel bearing that is provided on the center longitudinal axis of the conveyor pan and/or of the pan sections. Due to the center swivel bearing that is provided on the center longitudinal axis of the conveyor pan according to the invention, meaning a swivel bearing, which offers a hinged connection and moves the swivel point of adjoining pan sections to the center of the conveyor pan, the forces applied to the scraper chain belt are considerably reduced since the maximum bending between two adjoining pan sections is reduced by the center swivel bearing.
With the pan sections used until now in the state of the art, which sections are hingeably coupled to each other exclusively by the lateral pan section connecting means, bending automatically occurs between adjoining pan sections in a curve of the conveyor pan, which causes the sections to abut in the region of one of the two pan section connecting means and form a lateral swivel bearing, while on the opposite pan section connecting means the distance between the two pan sections is maximized. Consequently, the gap between two pan section connecting means continuously increases on the known pan sections from one pan section connecting means or from one lateral profile to the opposite lateral profile. This considerably varying bending of the pan sections in relation to their width, which bending occurs in curves of the face conveyor, resulted in the previously used pan sections in the fact that a double scraper chain routed in the conveyor pan experienced considerably more tension in the outer curve region of the chain strand than on the inner curve region of the chain strand, thus transmitting a larger portion of the conveying forces via the outer curve region of the scraper chain. The additional tension of the outer curve region of the chain belt relative to the inner curve region of the chain belt required the installation of a unit with higher drive output because additionally the tension forces must be overcome.
With the pan sections according to the invention, however, the elongation of the outer curve region of the chain belt relative to the inner curve region of the chain belt is considerably less due to the center swivel bearing, so that overall also the forces that are introduced in the chain links and consequently wear and tear are reduced. It is particularly advantageous that a pan strand is formed in the conveyor pan by a plurality of pan sections that are coupled to each other by means of center swivel bearings, so that the entire curve deviation can be substantially compensated for with relative uniformity across this pan strand comprising a plurality of pan sections. Even existing entry conveyors can therefore be converted to an entry conveyor according to the present invention in that a partial area of the pan sections of the existing entry conveyors is replaced with the pan sections according to the invention with center swivel bearings, while the remaining pan sections of the entry conveyor may continue to be or are made of regular pans with lateral swivel bearings.
According to an advantageous embodiment, in the conveyor pan a special pan section is formed at a distance from the pan strand comprising pan sections that are coupled to each other by means of center swivel bearings, which special pan section is in turn hingeably coupled to a pan section abutting thereon with a center swivel bearing that is disposed on the center line of the conveyor pan and/or the pan sections. The pan strand comprising the plurality of pan sections is consequently associated with an additional swivel bearing in the conveyor pan, which bearing enables counter-swiveling in a particularly simple manner, which in turn has the advantage that the swivel angles also on this single special pan section are less than in generic pan sections. Alternatively, at a distance from the first pan section a second pan section comprising a plurality of pan sections disposed behind each other may be formed, which sections in turn are hingeably coupled to each other by means of a swivel bearing disposed on the center longitudinal axis. It may also be sufficient, however, to provide only a single pan strand with a plurality of, for example six to fifteen pan sections with center swivel bearings in the entry conveyor. It is expedient if between the first pan section and the second pan section or the special pan regular pan sections are provided, which are hingeably connected to each other in a manner that guarantees tensile strength exclusively by receiving elements for pan section connecting means, which elements are disposed outside of the lateral profiles. It is furthermore expedient if the swivel bearing transmits substantially all pressure forces occurring in the conveying system between the abutting face ends of adjoining pan sections. For this purpose, it is advantageous if the swivel bearing at the same time effects good support for adjoining pan sections.
The invention is achieved even with a single pan section in that it comprises a swivel bearing formed at the center between the pan section connecting means or at the center between the lateral profiles to establish a hinged coupling of adjoining pan sections in the region of the center longitudinal axis of the individual pan sections or the conveyor pan formed by them.
According to an advantageous embodiment, the swivel bearing may be formed by projections on a conveyor base end and recesses on the opposite conveyor base end or the swivel bearing is established by the interaction of corresponding projections and recesses. Of course it is understood that on an entry conveyor the projection of a preceding pan section interacts with a recess in the conveyor base of the following pan section or vice versa. In an alternative embodiment, the top strand may be formed of an exchangeable trough, which can be inserted detachably in the pan section and is supported on an intermediate base formed between the two side walls of the pan sections, wherein the intermediate base on one base end may be provided with a projection and on the opposite base end with a recess for forming the swivel bearing. Furthermore, both the conveyor base and the intermediate base may be provided with appropriate swivel bearings.
Also with a fixed top strand, a pan section according to the invention may have an intermediate base on which the swivel bearing elements forming the swivel bearing, such as particularly the projection and the recess, are formed. To offer advantageous support of adjoining pan sections on the center swivel bearing, it is advantageous if the intermediate base comprises a center cross-member or the like, on which the recess is formed and which forms the projection for the swivel bearing. The swivel bearing may extend across a large depth, without excessively exceeding the total weight of the pan section. If it also advantageous if the intermediate base on an intermediate base edge is provided with an overlapping tongue for engaging in an overlapping taper of the opposing intermediate base edge.
Finally, providing center swivel bearings is also advantageous when the pan sections are configured as the ramp elements of a loading ramp, which ramp elements may then comprise the swivel bearing in the ramp element base or in the ramp element cover plates. In this embodiment, the center, swiveling coupling of adjoining pan sections is not established by means of the elements of the pan sections that form the conveyor pan, but instead by those elements that form the ramp construction. When configuring the pan sections as ramp elements for a loading ramp, it is particularly advantageous when the swivel bearing is formed by semi-circular overlapping projections on the ramp element base ends or on the ramp element cover plate ends, which at the same time serve or may serve the vertical support of the ramp elements against each other and preferably alternately engage in each other for the vertical support of the ramp elements.
In all embodiments, the swivel bearing may preferably comprise or be made of a semi-circular projection on one base end and a semi-circular recess on the opposing base end, which ends preferably have a relatively large contact region with each other in order to transmit all pressure forces present in the system between pan sections disposed behind each other. To minimize the chain elongation as a result of curves in the entry conveyor, it is particularly advantageous if the edges of the bases comprising the swivel bearings extend on both sides of the recess and/or of the projection at an angle toward the lateral profiles, so that the opposing, wedge-shaped widening edges substantially delimit the maximum swivel angle between two pan sections.
It is expedient if walls are mounted on both sides of the lateral profiles, which walls tower beyond the top strand in order to be able to transport also excavated material on the entry conveyor. It is also advantageous if at least one of the drive stations or return stations is configured such that it can be tensioned by means of tensioning cylinders. The tensioning cylinders may then advantageously be associated with pressure sensors, the signals of which are fed, for example, to a control unit for the tensioning cylinders and/or a monitoring device, to detect excessive bending within the entry conveyor.
Further advantages and embodiments of an entry conveyor according to the invention or the pan sections used for the same will be apparent from the description provided hereinafter of exemplary embodiments shown in schematic illustrations in the figures, wherein: